First, you need to be using a dynamic mic. The HD500 does not provide the phantom power that a condenser microphone needs.

On the Input Options page, you need to rotate the associated black knob beneath the display to change the parameter settings. Make sure the Inputs Setup is set to PRESET (knob/parameter #4). Then make sure one of the Input Sources (knobs 1 and 2) is set to MIC. Then adjust the Mic Trim knob beside the Mic XLR input until you can hear the microphone input. Then assign your desired amp/FX to the signal path(s).

1

Life is what happens to you while you're busy making other plans..... John Lennon